Ah, Easter!

The reason is obvious: it is always on the first Sunday after the first full moon after the first day of spring. Not expecting that were you? The key to it is in the name Easter itself.

The name came into English from an old Germanic goddess named Eostre, the goddess of the dawn. Her holiday was celebrated at the spring equinox, when the path of the sun, or the ecliptic, crosses the celestial equator, and the length of day and night are equal. She was also the goddess of fertility, therefore eggs, bunnies, and lambs were associated with her. She is cognate with the other Mediterranean fertility and love goddesses like Astarte, Ishtar, and Aphrodite, who were all considered aspects of the one mother goddess. There’s some scholarly arguments about all this, but I’m the quasi-scientist around here and this is my quasi-theory.

Now, how do we get from the equinox to the correct Sunday for Easter and what does it have to do with the moon and what all?

Many forms of the mother goddess had sons and the father was usually a sun god and the son was equated with the father. Many of these sons of gods died, and resurrected, for the sake of their followers, and they did it on, or near, the spring equinox. The path of the solar ecliptic and the celestial equator make an x where they cross, both in the spring and fall. These various sons of god, many of whom were crucified, died, in the spring, at the point when the sun is at the center of that big x mark in the sky, the big cross in the sky. Having your son of a sun god resurrect on a Sunday is highly appropriate. Most of these goddess mothers of a son of god were moon goddesses, so you had to get the moon involved, and the full moon has been associated with regrowth and fertility in many cultures.

On the other hand, officially, Easter Sunday is the first Sunday after the first full moon after the first day of spring because the bishops at the Council of Nicea voted to make it so in 325 AD. On the third hand, that council was ruled over by the Emperor Constantine, who had a hard time distinguishing Jesus from Solus Invictus, the form of the Persian god Mithras that he previously worshiped. Go figure.